The present invention relates to a belt driving device, a driving device, belt driving method, driving method, and image forming apparatus.
The image forming apparatus such as a copier, a facsimile, or a printer fixes a toner image onto a recording medium with heat, to make a copied or a recorded medium. Belt driving devices are known for use with an image forming apparatus.
A schematic front view of a background image forming apparatus of tandem type is shown in FIG. 22. The image forming apparatus includes four image forming members 1, four transfer rollers 2, a conveying belt 3, a feeding unit 6, a fixing device 7, and four developing units 8. According to this structure, each developing unit 8 forms a static potential image on each image forming member 1 into the visible static image as toner images. The feeding unit 6 sends the recording medium S along belt 3. The belt 3 is synchronized with respect to the application of the toner images forming on the image forming member 1. In this way, each transfer roller 2 sequentially transfers the toner images from each image forming member 1 onto the recording medium S, the toner images fixed onto the recording medium S at fixing device 7.
A schematic front view of another background image forming apparatus of tandem type is shown in FIG. 23. The image forming apparatus includes an intermediate transfer belt 4, and a cleaning member 9 in addition to the background image forming apparatus of FIG. 22. According to this structure, each transfer roller 2 sequentially transfers the toner images from each image forming member 1 onto the intermediate transfer belt 4. The toner images on the intermediate transfer belt 4 are transferred onto the recording medium S in a nip between the intermediate transfer belt 4 and the conveying belt 5. Then cleaning member 9 removes the residual toner from the intermediate transfer belt 4.
Japanese Published Unexamined Patent Application NO. Hei 10-268595 shows an image forming apparatus similar type to the image forming apparatus in FIG. 23. In this application, two pressing rollers, which press the intermediate transfer belt, are arranged across the nip where the toner images on the intermediate transfer belt are transferred onto the recording medium. Thus, velocity fluctuation arising at the nip is prevented from dispersing toward the portion not across the nip on the intermediate transfer belt. However this structure does not completely eliminate the intermediate transfer belt.